This invention relates to a fluid pressure monitoring device for mechanisms such as hydrostatic fluid bearings and more particularly, to a fluid pressure monitoring device for use in conjunction with pressurized fluid lines which monitoring devices constantly monitors the pressure of the fluid in the line and senses any decrease in such pressure below a predetermined minimum level. Furthermore, the device is adaptable for various forms of sensing arrangements, such as mechanically actuated switches, proximity sensors and auxiliary fluid flow detectors, any of which may be arranged to interrupt the operation of a machine when the decrease in fluid pressure to a vital component is sensed or detected therein. Still further, due to the unique arrangement of the fluid pressure monitoring device of the present invention, the same may also be adapted for mounting portions thereof on moving machine parts operating in coordination with portions thereof on stationary machine parts while still maintaining an efficient and positive fluid pressure monitoring operation.
There are many instances in modern, high speed, production and other types of machines wherein many of the vital working components and/or control components thereof are actuated and operably maintained functional by pressurized fluid, whether liquid fluids such as oil fluids such as air. In many cases, a supply of the pressurized fluid is absolutely required to a vital component of the machine in order for that component to perform its intended function and if such pressurized fluid supply is even momentarily interrupted, that particular component requiring such supply can be severely damaged or, at least, will malfunction so as to effect overall operation of the machine resulting in a major machine malfunction. Although, upon minor consideration, this may appear to be a relatively inconsequential problem, it is pointed out that with the extremely high speeds of modern machinery and the multiplicity of uses of fluid pressure for functional operation and controls, it can be seen that a relatively remote fluid pressure failure which may not be immediately easily detected can be the cause of expensive repairs and a serious loss of production time.
Prime instances of just such possible serious malfunctioning situations from an interruption of fluid pressure are clearly illustrated in U.S. Pat. No. 3,735,629, dated May 29, 1973 and entitled "Apparatus For Forming One-Piece Metallic Can Bodies." Briefly, the apparatus disclosed in said patent includes a horizontally reciprocal ram which successively engages each of a series of shallow drawn aluminum or tin plate cups forcing the same through a series of dies to ultimately produce relatively deep, final one-piece can bodies used as containers for merchandising various forms of liquids for human consumption. The speed of operation of the apparatus is extremely high, in the order of 150 to 175 reciprocal strokes of the ram per minute.
More important to the principles of the present invention, the high-spped reciprocal movements of the ram in such apparatus are produced by securing the ram to a reciprocal carriage which is, in turn, movably supported on the particular machine by a multiplicity of hydrostatic oil bearings. Each of the multiplicity of carriage oil bearings is comprised of a preferably circular oil bearing pad on the movable carriage acting against a stationary flat surface on slides of the machine with constantly pressurized and constantly flowing oil being emitted from the oil bearing pad against the slide surface creating a constantly flowing oil thickness between each pad and the flat slide surfaces.
Oil bearing pad and slide surfaces are positioned so that the ram carriage is stabilized in all directions as well as horizontally movable. It can be seen that such stabilizing for counteracting a multiplicity of forces is quite important, particularly in view of the fact that the ram is secured to the carriage in cantilever fashion so that the oil bearings are required to not only support the carriage and the ram during the high-speed movement, but also to counteract the varying forces resulting from this ram cantilever mounting during such movement, all of which must be maintained with extreme accuracy. Furthermore, with the carriage and ram constantly moving in the required reciprocal strokes and the fact that the hydrostatic oil bearings each require a constantly flowing supply of oil thereto for functioning, the constantly flowing oil supplies to the individual carriage oil bearing pads must be through flexible conduits even further increasing the overall possibility of difficulties from pressurized oil supply malfunctions.
Despite all of the foregoing, however, it can be seen that the failure of functioning of any one of the many carriage hydrostatic oil bearings can result in serious consequences. Whether the particular hydrostatic oil bearing is for purposes of support or for purposes of stabilization and alignment, failure of the pressurized oil supply thereto can immediately not only cause misalignments in the carriage and ram movements, but can permit direct contact between the moving carriage oil bearing pads and the stationary slides involving serious injury to the respective parts and the expense of replacement thereof. It is vital, therefore, that the pressurized oil supplies to the moving carriage oil bearing pads be constantly monitored and upon the initial failure of any one of these pressurized oil supplies, the machine be quickly stopped before serious damages can occur.
In addition to the above described support for the moving ram of the machine, a hydrostatic oil bearing sleeve is provided forwardly of the ram carriage path of movement and within which a portion of the moving ram is always supported. This hydrostatic oil bearing sleeve mounted stationary on the machine includes four axial slots radially therethrough spaced circumferentially equidistant about the ram periphery. Again, pressurized oil is directed through these sleeve slots and against the ram periphery creating constantly flowing hydrostatic oil thicknesses between the ram and sleeve.
The hydrostatic oil bearing sleeve, therefore, in effect comprises four peripherally acting hydrostatic oil bearings and by proper pressurized oil supply to each of these bearings, the moving ram may be supported intermediate its length and maintained in proper desired alignment necessary for proper machine functioning. Furthermore, failure of the proper pressurized oil supply to any one of these oil bearings can again very quickly cause misalignments of the ram and possible serious damages. For these reasons, constant monitoring of the pressurized oil supplies to the hydrostatic oil bearing sleeve is highly desirable so that the machine can be immediately stopped in the event of a detected malfunction.